Electric meter.



PATENTED JULY 23, 1907.

W. J. MOWBRAY. ELECTRIC METER. APPLICATION FILED JULY20,1905.

2 SHEETS-SHEET 1.

Fig. 2."

Witnqsses a t .r .fi cub w, o n J m m UNITED STATES PATENT OFFICE.

WILLIAM J. MOWBRAY, OF BROOKLYN, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

- ELECTRIC METER.

Specification of Letters Patent.

Patented July 23, 1907.

Application filed July 20. 1905. Serial No 270.453

To all whom it may concern:

Be it known that I, \VILLIAM J. Mownaav, a citizen of the United States, residing at Brooklyn, county of Kings, State of New York, have invented certain new and useful Improvements in Electric Meters, of which the following is a specification.

This invention relates to electric measuring instruments and particularly to portable integrating wattmeters adapted for use in testing wattmeters installed on customers premises.

Experience has shown that it is quite necessary to pcriodically test the integrating wattmeters now commonly used to measure the energy consumed by customers, and also that these tests should be made under actual working conditions, that is, while the meter is mounted in position on the premises of the customer.

' This can be done with electric indicating instruments and a stop watch, but it has been found much more satisfactory and convenient to use a portable integrating wattmeter specially constructed to facilitate making the necessary tests as testing in this way requires much less apparatus, avoids the use of a stop watch, reduces considerably the amount of calculating necessary, and greatly increases the number of meters that can be tested in a given time.

My invention comprises a portable, integrating wattmeter or test meter similar in many respects to the wattmeters now in common use but provided with a number of special features the purposes of which are to facilitate connecting the meter in circuit with a customers meter in the proper manner and making the necessary tests;

to adapt the meter for use in testing meters of various types and capacities, and to eliminate errors inherent in an ordinary meter when used as a testing instrument.

The novel features which I believe to be characteristic of my invention will be definitely indicated in the claims appended hereto.

The details of the construction and the method of using my improved test meter will be better understood by reference to the following description taken in connection with the accompanying drawings.

The features of my invention are illustrated and described as applied to an integrating induction motor but 1 do not wish to be understood as limited in this respect as some of the features of my invention are equally applicable to integrating meters of the commutating motor type.

In the d rawiugs, Figure 1 is a perspective view of the meter with the cover removed; Fig. 2 is a back view of the meter removed from the inclosing box with the top plate in central section; Fig. 3 is a detail of the switch in the potential circuit; and Fig. 4 is a diagrammatic view showing tlc electrical connections.

The instrument consists of an integrating wattmcter of standard construction changed inseveral respects to facilitate testing. The motive part of the meter com prises a rotatable armature 1 which consists of the usual conducting disk and the stationary magnetic circuit with its energizing coils. Disk 1 is carried by a shaft 2 which is supported in the usual manner on a jewel bearing carried by the frame 3. The stationary magnetic circuit consists of two laminated cores 4 and 5 secured to frame 3 by bolts 6. The arrangement of the magnetic circuit and its coils will be best understood by reference to Fig. 4. In that figure, core 4 is shown with three parallel members connected at the top, with the potential coil mounted on the central member. Core 5 hasits extremities extended into close proximity with the three members or poles of core 4, thereby forming with core 4 a nearly closed magnetic circuit for the potential coil, whereby current in the coil is lagged in a manner well understood in the art. Core 5 is provided with two poles facing the central pole of core 4 on which poles the series or current winding of the meter is placed. The disk armature l is disposed between the poles on which the series coils are placed and the central pole of core 4. The leakage magnetic flux of the potential coil which does not pass through the nearly closed circuit offered by the extremities of core 5 passes from the central pole of core 4 through the disk to the poles on which are mounted the series coils.

The series coils on the two poles of core 5 are 0ppositely Wound and produce fluxes which, with the flux from the central pole of the core 4, produce a shifting resultant field and consequent rotation of the disk in a manner well understood in the art. A short-circuited coil 7 is mounted on the middle pole of core 4 and assists the flux through the disk to the poles of the series coils and thereby produces the 90 displacement of the potential flux from that of the series coils in a manner well understood. In order to compensate for the starting friction, a closed circuit 8 is suspended directly above the disk 1 and surrounding the central pole of core 4 and is arranged to be horizontally adjustable to vary its compensating effect. Secured to the frame 3 of the meter is a plurality of permanent magnets 9 whose fields are cut by the disk armature 1 to retard the rotation of the moving element of the meter. A more detailed description of these parts of the meter is not considered necessary as they form no part of my invention.

The meter is secured to the under side of a top plate 10 of insulating material by screws 11 extending when the meter is not in use and a strap may be secured to the box by which the metermay be suspended from the shoulder. The shaft 2 of'the moving element is extended above its upper hearing which is located in an opening in the plate 10 and on its upper end carries an indicator 13 which moves over a scale 14 preferably divided off into ten equal parts each of which is subdivided as shown in Fig. 1. A second indicator 15 is geared to the shaft 2 and preferably arranged to rotate at one-tenth of the speed of shaft 2, In practice it is found that this arrangement of the indicator is most convenient as it permits of reading meter while working on the full load and also on a light load, for instance, one-tenth of its full load; also,

it is necessary to test meters of widely varying capacities. In order to permit .making such tests,1 provide means for obtaining the full load torque of the test meter on widely different loads so that, for each test, the test meter can be run under conditions giving the greatest accuracy. This can be done by providing a series winding of a plurality of turns on the poles of core 5 and connections for including more or less of these turns in circuit on the different loads, the turns being so wound and connected that the portions included in circuit 011 the different loads will give the proper inductive effect. I prefer, however, to provide a plurality of separate and distinct series coils.-

In the drawings I have shown three such coils, 16, 17 and 18 on the poles of core 5, each of which is arranged to produce the full load torque of the meter though on widely different loads. In other words, the number of turns in each of the series coils 16, 17 and 18 is such that each coil give the same number of ampere turns onthe load [or which it is designed as each of the other coils on the load-for which it is designed. Preferably the several series coils are so proportioned that one can be used to test a customers motor on' full load and the next one on light load, the full load torque of the test meter being obtainod in each case so that it is running under conditions conducive to grcatcst ac curacy. Mounted on the top plate l0, on the lefthand side, are four binding posts ll), 20, 21 and 22. One side of each of thc scrioscoils l6, l7 and I8 is connected to the binding post lfl and tho.othor sides of the three coils are conncctcd to tho posts -20, 2i and 22, rospoctivcly so that by connecting the tcrminals of onc of tho lincs cnlcring a customcfis promises to the binding post If and one ol' lhc other thrco binding posts, (in: proper scrics coil can bc sclcctod and connected in scrics in that linc so that the current in the coil-will vary with tho currcnlv consumed in the dcviccs which are conncctcd in circuit,

in many lighting syslcms both two-wire and lhrccwirosyslcms ol di.-:tribution ol clcctric oucrgy are omploycd and in thrcc-wiro systcms some of the motors huvo the potential circuit conncctcd across the two outside mains of tho systcm, whilo in olhcrs itis conncctcd between one of the outside mains and the houtral. In order to adapt my instrument for testing meters of both of these classes, I wind the potential coil of the test meter in two equal coil sections and provide a switch by which the sections may be connected in series or in parallel, the connections being such that in both cases the magnetomotive force of the two sections of-the potential coil is cumulative. The two sections of the potential coil are indicated at 23 and 24. Mounted in the top plate 10 is a switch consisting of a stem 25 extending through an opening in the top plate 10 and carrying a knurled head 26 at the top and a cylindrical member 27 at the bottom below plate 10, the latter being formed of insulating material with two metallic conducting segments 28 and 29 secured thereto. Mounted on the under side of plate 10 are four insulated brushes 30, 31, 32 and 33. A stop 54 is arranged to limit the turning movement of the switch so that at one limit of its movement segment 28 connects brushes 30 and 31, and segment 29 connects brushes 32 and 33, and at the other limit of its movement, segment 29 connects brushes 31 and 32. As shown in Fig. 4, the terminals of coil 23 are connected to brushes 30 and 32 and the terminals of coil 24 to brushes 31 and 33.- Mounted on the top plate 10 are two potential binding posts 34 and 35, the latter of which is connected to the brush 33. The post 34 is connected to brush 30 through a push button switch 36 biased to open position which may be closed by pressing a but: ton 37 extending up through an opening in the top plate l0.-

In making a test, the test meter is connected in circuit with the customers meter by connecting one of the series coils 16, 17 or 18 in series in one of the lines and the potential coil across the two lilies. The series coil is connected in circuit by connecting one terminal 106 of one of the lines to the binding post 19 and the other terminal of that line to the'binding post 20, 21 or 22 leading to the coil 16, 17, or 18, respectively, which, on the load at which the test is to be made, will give in the test motor a torque most nearly approaching the 105 full load torque. To connect the potential coil in circuit the binding posts 34 and 35 should be connected each to one of the lines though this circuit is not closed until the button 37 is depressed. I If the system is a two-wire system of the usual voltage, or if it is a 110 thrcc-wirc system and the potential circuit of the motor is connected across one of the outside lines and the ncutral, the switch in the potential circuit is turned by moans of the knurled head 26 to bring it to thc o-' sition shown in Figs. 3 and 4 in which the two coil scc- 11.5 tions 23 and 24 of the potential coil are connected in parallel, the connections bcing from binding post 34 to brush 250 and from there through scctiou 23 to brush 3 2, segment 25) and brush 33 to binding post 35 and also l'rom brush 30 through segment 28 to brush 31, scc- 120 tion 24, brush 33, and thcn to binding post 35. If the system is a thrcc-wirc systcm with the potcntial cir cuit ol' the motor conncctcd across the two outside lincs, the switch is turned to the other limit of its range of movcnn-nt in which position scgmcnt 29 bridgcs brushcs 21d and 32 and the polcntial circuit in this case is from binding post 34h) brush 30, through coil scction 225 to brush 32, scgincut 2.) to brush 3!, section 24 to brush 33 and thou to binding post 35 so that the two sections of the potential coil are conncctcd in load.

series. It will be seen that the two sections of the potential coil are so wound and connected that in either case they exert cumulative inductive effects. Suitable devices consuming electric energy are then cut into circuit until the desired load is obtained, where- The operator then presses the button releases the button 37, whereupon the moving elc- I ment of the test meter comes to rest. The humbcr of revolutions made by the moving element of the test meter can then be read on the dial of the test meter and the ratio of the revolutions made by moving elements of the customers meter and of the test meter gives the percentage of accuracy of the customers meter. The load is then reduced to a fraction of the full load oi the customers meter and the series coil 16, 17 or 18 is connected in circuit which willgive as near as possible the full load torque of the test meter at that This is done by merely changing the connection to one of the binding posts 20, 21 or 22 to another of those posts. A similar test is then made to get the light load accuracy of the customers meter.

l have found it advantageous in some cases to provide means whereby the revolutions of the moving clement ol' the test mctcr can be counted while watching the customers meter. 1 accomplish this by providing a telephone receiver and means whereby the moving element of the lest meter closes a circuit through the receiver momentarily once in each revolution. Secured lo the shalt 2 of the meter is a pin 38, aml a light flexible brush 3!) is mounted in position to be lightly engaged by the pin to close an electric circuit once in each revolution of shaft 2, the circuit being coinplcicd through the telephone receiver by the frame ol' the meter, the dial and other parts to shalt 2. In some types of.meiers the current for the telephone rccciver may be obtained by closing a shunt around a resistance of small ohmic value, but in a meter of the type illustrated in the drawing prefer to supply this currenl by induction. On the central leg of core 4 is a coil l0 which may consist oi only one or two turns in which a current of very low voltage is induced in a nldlilltldi'lll undcrslood in lhc art. One terminal of this coil is connected to thc frame 3 ol' the meter as indicalcd al ii and lhc other terminal to a binding post -ll uiounlcd on the top plate 10 of the meter. A wcond binding post 42 mounted on platc I0 is con ncclcd lo the brush 39 which is insulated from iramc ii. The telephone receiver 4?. ilcxiblc lcad-s by which conncclion is made lo the binding posts ll and 42. it will be seen that in each revolution of lhc moving clcmcnl. ol the lcst meter the pin 38 cugagcs brush ilil momentarily lhus closing the circuit ol' coil ill. lhc circuil bciug llhlll coil -10 to bindlhrough the receiver l3 lo binding post pin 33. shalt 2, then log post ll. ii to lllc iusulal-cd brush Iii).

. through lhc bcaringsnml dial to thc frame 3 to which coil ill is con'n-clcd.

lhc lcsl. lnclcr in the manner (he olhcr sidc ol' \\hcu using lhc receiver. in circuit with the customers luclcr is connected above described. The operator holds the receiver 43 to his ear and by counting the clicks occasioned by the momentary closure of the circuit of the receiver he can count the number of revolutions oi the moving element of the test meter while watching the moving element of the customers meter. If the disk of the customers meter is marked off to 'ascalo or ii a printed scale is secured thereon, the operator asccrtains the number of revolutions or fractions of a revolution made by the moving element of .he customers meter while the test meter is making a definite number o revolutions, preferably ten. The:accuracy of the customers met r is then found as before. As the ratio in this case is based on ten'instead of on the number of revolutions made by the moving element of the test meter while that of the customers meter is making ten revoluis provided with long l l l -cuiuul:ilivc inductive cliects.

tions, the accuracy of the customers meter can be de' termined immediately with suiiieient exactness without restoring to an exact calculation.

I do not wish to be understood as limited to the exact construction which I have illustrated and described herein as many modifications can be made therein without departing from the spirit of my invention; all such modifications I consider within the scope of my invention and I aim to cover them by the terms oi the claims appended hereto.

What I' claim as new and desire to secure by Patent of the United States, is:-

1. An induction meter comprising a magnetic core, a

potential coil thereon, a second core. a series winding thereon. a plurality of binding p'osts, connections from said binding posisto different points on said series winding. and an armature mounted for rotation be weenisaid cores. H

2.. An induction meter comprising a magnetic core. a potential coil thereon, a second core, a plurality of series coils thereon. an armature mounted for rotation between s: id cores. and binding posts to which the several serles coils are connected.

3. An induction meter Letters comprising a magnetic core, a

potential coil thereon. a second core. a plurality of series coils thereon, an armature mounted for roration between said cores. a binding post to which one side of each of said series coils is connected, and a plurality of binding posts to each of which the other side of one of said coils is connected.

4. An integrating electric meter comprising a moving element. a current coil in inductive relation thereto, a shunt circuit. two binding posts, and a switch ranged to connect the shunt circuit between said binding posts in one position and in the other position to divide said shunt circuit into two parts of substantially equal vresistance and connect said parts in parallel between said binding posts.

5. in an integrating induction meter, a potential coil consisting of a plurality of coil sections and means for connecting said sections in series or in parallel with cumulaiivc inductive effects.

d. An integrating induction meter comprising a magnetic core, a potential coil consistingof a plurality of coil sections thereon. means for connecting said coil seclions in series or in parallel with cumulative inductive effects, a second core. a current coil thereon, mounted for rotation between said cores.

7. In an lnlegrating induction meter, a potential coll consisting of a plurality of coil sections, two binding posts. and a switch ranged to connect said coll sections helwccn said binding msts in series or in parallel with 8. An integrating induction meter comprising a support, a li-ainc secured thereto, a magnetic core carried by the frame. a potential coll consisting, of a plurality of coil sccllons on said core. a switch mounted'on said support and arranged to connect said coil sections in series or in and a disk armature parallel with cumulative inductive eiiects, a second core, a current cell thereon, and a disk armature mounted for rotation between said cores. 1). An integrating electric meter compr element a current cell in inductive ICltltl'OD thereto, a shunt eult divided into two parts of substantially equal resistance, a switch arranged to connect said parts in series or in parallel, and a switch normally biased to an open circuit posi on included in said shunt circuit. It). An integrating induction meter comprising a moving element, a plurality of series coils mounted in inductive relation thereto, means for connecting any one 01' i ing a moving I said series coils in circuit, a shunt coil also mounted in inductive relation to the moving element and comprising a pluralityof coil sections, and means for connecting said coitsections in series or in parallel with cumulative iir ductive effects. 1

ln witness whereof I have hereunto set my hand this Hill day 01" July, 1905.

wnnflnm J. MOWBRAY.

Witnesses Jos. C. I'IneKi-ni, Jr.,

Josnrn JACKSON. 

